Danfoss TG230 Series, Installation Manual

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Page 57 of 108
M-AP-001-EN Rev. N
Guide Specifications
This section contains written specifications for the TT and TG series compressors for use in
system design specifications.
12.1 General
12.2 Refrigerant
12.3 Compressor
Bearings
12.4 Capacity Control
12.5 Compressor Motor
12.6 Compressor
Electronics
12.6.1 Ancillary Devices
Construction shall utilize a two-stage, variable-speed, centrifugal compressor design
requiring no oil for lubrication. Compressor shall be constructed with cast aluminum casing
and high-strength thermoplastic electronics enclosures. The two-stage centrifugal impellers
shall consist of cast and machined aluminum. The motor rotor and impeller assembly shall
be the only major moving parts.
TT compressors shall be designed for use with R134a while TG compressors are designed for
use with R1234ze(E).
The compressor shall be provided with radial and axial magnetic bearings to levitate the
shaft, thereby eliminating metal-to-metal contact, and thus eliminating friction and the
need for oil. The magnetic bearing system shall consist of front, rear, and axial bearings. Both
the front and the rear bearings are to levitate the shaft at X and Y directions, and the axial at
Z direction. Each bearing position shall be sensed by position sensors to provide real-time
repositioning of the rotor shaft, controlled by onboard digital electronics.
The compressor shall have a Variable Frequency Drive (VFD) for linear capacity modulation,
high part-load efficiency and reduced in-rush starting current. It shall include an Insulated
Gate Bipolar Transistor (IGBT) type inverter that converts the DC voltage to an adjustable
three-phase AC voltage. Signals from the compressor controller shall determine the inverter
output frequency, voltage and phase, thereby regulating the motor speed. In case of
power failure, the compressor shall be capable of allowing for a normal de-levitation and
shutdown.
Compressor speed shall be reduced as condensing temperature and/or heat load reduces,
optimizing energy performance through the entire range of capacity. Capacity modulates
infinitely as motor speed is varied across the range. Inlet Guide Vanes (IGVs) shall be built-
in to further trim the compressor capacity in conjunction with the variable-speed control
to optimize compressor performance at low loads. Refer to DTC Selection Software for
performance calculations and limits.
The compressor shall be provided with a direct-drive, high-efficiency, permanent-magnet
synchronous motor powered by pulse-width-modulating (PWM) voltage supply. The motor
shall be compatible with high-speed variable-frequency operation that affords high-speed
efficiency, compactness and soft start capability. Motor cooling shall be by liquid refrigerant
injection.
The compressor shall include a microprocessor controller capable of controlling magnetic
bearings and speed control. The controller shall be capable of providing monitoring,
including commissioning assistance, energy outputs, operation trends, and fault codes via a
Modbus interface.
A check valve shall be installed on the discharge port of the compressor to protect against
backflow of refrigerant during coast down. It is recommended that the valve be located
after the properly designed discharge cone adaptor, preferably close to the condenser in the
packaged system. The system shall also be provided with an appropriately sized line reactor.
12 Guide Specifications